The Chytridiales is the largest (about 80 genera and 500 species) of the five chytrid orders and, as pointed out by James et al., the order most in need of taxonomic reorganization. Based on 18S sequence data, four separate clades have been identified within the order Chytridiales (James et al. 2000). These are the Chytridium clade, the Lacustromyces clade, the Nowakowskiella clade, and the Rhizophydium clade. Some species, which are definitely in the Chytridiales, do not cluster within these clades, e.g., Batrachochytrium dendrobatidis and several other unidentified isolates.
Our PEET group is located at three universities with each site specializing in a different area and providing access to equipment and training needed by members at other sites. PEET members Sharon Mozley and David Porter at the University of Georgia are studying the Nowakowskiella clade, working out generic definitions by following development at the light microscopic level, checking zoospore ultrastructure in the TEM, and carrying out sequencing of the 18S and other genes. At the University of Alabama in Tuscaloosa, Martha Powell, Pete Letcher, and Jimmy Chambers are working on the Chytridium clade, as well as developing a new method of DNA isolation from agar cultures. They also are working on developing chytrid-specific primers for the sequencing of mitochondrial genes. As part of the three site partnership, UGA will work on developing primers for genes such as RNA polymerase B and sequencing cultures sent to them by the other two sites and vice versa with UA creating primers for mitochondrial sequences and sequencing cultures sent to them by UGA and UMaine. At the University of Maine, Joyce Longcore is continuing to explore the diversity of the Chytridiales by searching for and studying isolates that do not cluster within the major chytridialean clades. She supports the work at UGA and UA by leading tutorials on collection, isolation, and other techniques for PEET graduate students and others who have an interest in chytrids, and by supplying cultures from her culture collection.
Each link in the list below will take you to an individual page for each clade. A short description of the clade is given along with a list of genera, images, and references.